They protect damaged arms stolen using this kid's toy (9)
I believe the answer is:
slingshot
'toy' is the definition.
(I know that slingshot is a type of toy)
'they protect damaged arms stolen using this kid's' is the wordplay.
I cannot really see how this works, but
'arms' could be 'shot' (shot is a kind of arms) and 'shot' is present in the answer.
The remaining letters 'sling' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for slingshot that I've seen before include "fatal to Goliath" , "No slights (anag) - catapult (US)" , "Sing Holst? (Anag)" , "enough to knock you out" , "Catapult -- thin gloss (anag)" .)